Notes from the Test Bench
By Bruce Hofer, Chairman & Co-Founder, Audio Precision
This month is a big one at AP, as we release the new APx500 v3.0 software, our much anticipated PDM option, and our new PESQ software option for APx500. With the introduction of these products, the APx line of analyzers offer an extremely flexible set of tools for engineers working on smartphones and tablet devices, from design to verification to production.
We are excited to be presenting our products in a new venue: AES Brazil, May 8th through the 10th. And we'll be participating in another Bluetooth UnPlugFest in June, this time in Shanghai, China. At the most recent UPF in Vancouver, Canada, our APx analyzer with the Bluetooth option made quite a splash, as manufacturers could finally see and diagnose elusive problems with Bluetooth audio, some of which they didn't even know they had.
If you are in one of these corners of the world, we hope to see you. As always, Audio Precision looks forward to being part of your success in sound.
Output: What's New in APx500 v3.0
APx500 v3.0 is available for immediate download.
APx500 v3.0 brings support for both the PESQ software option and the new PDM Option module, improves Digital Serial (DSIO) functionality and streamlines the UI.
Our new PDM (Pulse Density Modulation) option is now available for the APx525 and APx585 analyzer families. PDM is used extensively in smartphones and tablets that employ digital MEMS microphones, and this segment of the industry is experiencing explosive growth.
The APx PDM option provides direct connectivity for audio devices that have a PDM output or input, including microphones and chipsets. The complete range of PDM data is available, from analysis of the audio passband to the raw bitstream. In addition to APx's audio measurements, the APx PDM option provides a variable DC power supply for tolerance and PSR (power supply rejection) tests, and supports the complete range of industry standard PDM sample rates, modulator orders and interpolation ratios.
A PESQ measurement software option is now available for APx500 v3.0.
PESQ (Perceptual Evaluation of Speech Quality) is a widely used perceptual measurement for voice quality in telecommunications. It was developed by OPTICOM GmbH in Germany and forms the basis of ITU-T Recommendation P.862. PESQ is specifically designed for testing voice quality on low bandwidth devices such as telephones, smartphones and hands-free devices. MOS (Mean Opinion Score) results from PESQ achieve a very high correlation with results obtainable using human subjects in a way that is faster, more repeatable, less expensive, and fully automated.
The APx PESQ software option supports the averaging of multiple PESQ measurements.
A single PESQ MOS measurement can vary depending upon test material and other factors that many vary with time, such as network quality. For this reason, it is often important to perform multiple instances of a PESQ measurement and average the results. This functionality is built-in to the APx500 PESQ measurement, allowing a single MOS value to be calculated based upon many individual test results. When this is combined with the new markers and labels on X-Y graphs, it is easy to identify outliers or problematic PESQ test samples.
Digital Serial I/O Improvements
DSIO Support for 16 Channels of TDM
The APx DSIO option now supports 16 channels of TDM audio data at sample rates up to 96 kHz. Previously the limit was 8 channels.
DSIO Support for Variable TDM Word Length
The APx DSIO option now allows users to specify the length of an audio word in TDM format, up to 128 bits. This is useful in situations in which the TDM word is padded with additional data or zeroes, allowing users to specify which part of the TDM word contains audio data.
DSIO Support for Left or Right MSB
The APx DSIO option now allows users to select whether the MSB of a data word is left or right justified.
DSIO Enhanced Frame Clock Support
The APx DSIO option now supports additional flexibility in defining the frame clock.
User Interface Improvements
New Signal Path Setup
While previously this section had incorporated a graphic of the specific audio analyzer being used, it is now streamlined in order to allow more room for the graphs in the Results Selector.
Signal Path Setup in APx500 v3.0
The location of the navigation controls for Signal Path Setup have also changed. Previously, each measurement pane contained a button for Signal Path Setup, and Signal Path Setup itself contained a "Back" button to return to the last-used measurement pane.
To create more room for valuable functions, we've moved both the Signal Path Setup and Back buttons to the upper left corner of each measurement pane:
Accessing Signal Path Setup in APx500 v3.0
This change provides greater consistency for you, while the functionality remains the same.
Markers and Labels on X-Y Graphs
PESQ results with markers
We've added a new feature to APx500 Graph Properties that allows you to Show Markers, which provides automatic labeling of data points for both X and Y axes. With the introduction of our new PESQ measurement option, it became clear that there was a need in some cases for users to be able to identify specific test points on a graph - especially when data has a low number of data points and a substantial space between points.
Report Properties Menu
The ability to change Report properties is now available directly in the Project menu of APx500, under Edit Report Properties.
API for Graph Export of Specified Size
The APx500 API now supports export of any results graph at size specified in pixels. This allows for increased quality of custom reports.
Continuous Sweep Crosstalk with User-definable Inter-channel Delay
The Continuous Sweep Crosstalk measurement now includes the ability to define a Channel Delay of up to 5.0 seconds. This may be used to eliminate issues with transient crosstalk.
Test Results: AP News & Events
AP Calls for Audio Consultants
AP is inviting audio consultants to apply to become an “Audio Precision Preferred Partner”. Preferred Partners are trained by AP to be proficient with our instruments and API. AP often refers customers to our Preferred Partners when they need audio test consulting services. Contact firstname.lastname@example.org for more information
Questions? Contact email@example.com for more information or to request a demo of Audio Precision analyzers.
© 2012 Audio Precision, Inc.